1.500 Which release of X11 do I have?

AIX 4.x includes X11 R5 and Motif 1.2.

On AIX 3, Run 'lslpp -h X11rte.obj'.
If your output has a line similar to:

            01.02.0000.0000 COMPLETE   COMMIT     03/04/93   02:05:11 root

you have X11 R4. If your output has a line similar to:

    U491068 01.02.0003.0000 COMPLETE   COMMIT     07/28/93   12:50:42 root

you have X11 R5. Some people also call these AIXwindows 1.2.0 and
1.2.3.  'lslpp -h X11rte.motif1.2.obj' should tell you if you are
running Motif 1.2.

From: Jan Just Keijser <KeijserJJ@logica.com> 

AIX 4.1 and AIX 4.2 come with X11R5 and Motif 1.2.4

AIX 4.3.1 (and perhaps 4.3.0) comes with X11R6.1 and Motif 2.1

Some executables which run fine using the X11R5 libraries may not run
when using the X11R6.1 libraries; you can specify which X11 libraries to
use by setting
  LIBPATH=/usr/lpp/X11/lib/R5:/usr/lib:...
for X11R5 and
  LIBPATH=/usr/lpp/X11/lib/R6:/usr/lib:...
for X11R6.1; by default,
    /usr/lib/libX11.a -> /usr/lpp/X11/lib/R6/libX11.a
and also for the other libraries on AIX 4.3.1.

On most of the AIX 4.1.x and 4.2.1 boxes I have seen the default is
  /usr/lib/libX11.a -> /usr/lpp/X11/lib/R4/libX11.a
ie the default libraries are the X11R4 libraries and _NOT_ the R5
libraries; this may also be due to the setup at my site.